Screwed conveyor belt fastener

ABSTRACT

The fastener ( 1, 2, 3 ) comprises for the screwing of screws, dimplings ( 5, 5 ′) set in a fixation plate ( 2 ) of the fastener. The dimplings ( 5, 5 ′) are attached to the fixation plate ( 2 ) in which they are made only on one part of their circumference, two reserved zones ( 81, 82  or  81′, 82 ′) for each dimpling not being stamped at the base of the dimplings and comprising shearings in the sheet metal of the fixation plate ( 2 ), allowing a certain tilting of the dimpling ( 5  or  5 ′) during operation of the conveyor belt.

The present application is the national stage under 35 U.S.C. 371 ofPCT/FR00/00927, filed Apr. 11, 2000.

Fasteners are known for joining conveyor belts, belts and similarproducts which comprise hinge elements and are likely to be fixedastride an end of a conveyor belt, the hinge elements being able to beplaced between similar hinge elements, belonging to a similar fastenerfixed at the other end of the conveyor belt, the two fasteners beinglinked by a linkage and articulation pin passing alternately through ahinge element of one of the fasteners and then through a hinge elementof the other of the fasteners.

This general type of fastener can be linked to the end of a conveyorbelt by rivets, nut and screw systems, flange-back nails, twin-pointstaples. These rivets, screws, nails or staples are passed through holesalready pierced in the upper half of the fastener, crossing through theconveyor belt, and then through holes already pierced in the lower halfof the fastener, and are locked from the other side by forming a secondrivet head, by tightening a screw, or by bending the ends of the nailsor the twin point staples.

The major problem faced by these very rigid fixation systems is therupture of the rivets, screws or pins of nails or staples, caused by thestrains undergone by these rigid assemblies when the conveyor belt isoperated under severe conditions. Even the twin point staples can break,in particular because of the strains imposed when the conveyor beltpasses over the forward or backward rollers. Such breaks cause damageand involve repeated stoppages for repairs.

The aim of the present invention is to develop a new fastener forconveyor belts in which the means of fixation is constituted of screws,but in which the ensemble of the means used allows a certain flexibilityof screw linkage of the two halves, upper and lower, of the fastener,this flexibility being indispensable to ensure the lifetime of thelinkage and/or fastener, because of the difference between the path ofthe lower face and the upper face of the conveyor belt, at the moment ofpassage over the forward and backward rollers.

This problem is solved by using a joining fastener for the conveyorbelt, comprising two fixation plates linked by U-shaped hinge elementspresenting, in one of the fixation plates, holes allowing the passage ofa screw and holding its head and in the other fixation plate dimplingswhich are oriented towards the first fixation plate, the screws passedthrough the holes of the first fixation plate being able to be screwedin the dimplings which are arranged in line with the corresponding holesof the first fixation plate when the fastener is tightened on a conveyorbelt end, characterised in that the dimplings, at their base, presentsteps extending over a part of their external circumference, butseparated by two circular sectors without diametrically opposed steps,generally oriented in the longitudinal direction of the conveyor belt onwhich the fastener according to the invention is set (or will be set),the material of the fixation plate being sheared at the position ofthese non-deformed circular sectors so as to allow the formation of thestep partially surrounding the dimpling by stamping of the base plate.

In an embodiment of the invention, the dimpling is threaded internallyfor the pitch of the screws used to fix the fastener on the end of theconveyor belt. However, such threading is not absolutely necessary sincewhen the dimpling has a smooth surface, the use of self-threading screwsgives an excellent grip, especially since in the case of normal use,these screws are never unscrewed and re-screwed.

Advantageously the holes in one of the fixation plates destined for thepassage of screws are given an opening in the form of a cup allowing thescrew heads to lodge there so that they do not pass through the externalface of the fastener.

As the steps made by stamping the dimplings form a cup on the externalside of the plate provided with dimplings, even if the screws pass alittle further than the chimney of the dimpling, the length of thescrews can be such that the end of the screws does not go beyond theplane of the external face of the fixation plate provided withdimplings, that is to say that the end of the screws is in the spacecomprised between the base of the dimpling chimney and the plane of theexternal face of the fixation plate provided with dimplings.

Thus, the joints do not have any asperities which, otherwise, could beconstituted of screw heads or their ends.

One embodiment will now be described as an illustrative example inrelation to the drawing in which:

FIG. 1 represents a fastener according to the invention seen inperspective,

FIG. 2 is a cross-section along the line II-II of FIG. 1, of thefastener according to the invention in FIG. 1, the fastener beingclamped back and the screws beginning to be tightened,

FIGS. 3 and 4 show the operational functions of the fastener accordingto the invention.

FIG. 1 represents in perspective such a fastener, presentedindividually, but being able to be manufactured in strips of fastenersof the same type, linked by short metal bridges. Note the elements ofthe hinge 1, U-shaped, a lower half 2 and an upper half 3. The upperhalf comprises two holes 4, 4′ set on the side opposite to that of thehinge elements. These holes comprise cups 41, 41′ to serve for restingthe heads of the screws. The lower half comprises two dimplings 5, 5′made in the metal and which show a central hole forming a cylindricalchimney 6, 6′. These dimplings are oriented towards the other half ofthe fastener, thus, once the fastener is mounted, towards the lower faceof the conveyor belt.

The fastener of FIG. 1 is shown as it is delivered, that is to saybefore mounting on the end of a conveyor belt. It is to be noted that itis open, the two halves, upper and lower, only being clamped one on theother at the moment of mounting, when gripping the end of the conveyorbelt. Note that from the internal side of the lower half, the dimplings5, 5′ show a step 8, 8′, 8″ 8′″ which does not complete thecircumference, this step being interrupted in 81, 82 and 81″, 82′. Theexplanations for this will be given below.

FIG. 2 shows a cross-section along the line II—II of FIG. 1 with onefastener folded, the two upper and lower halves being at leastapproximately parallel and the holes 4, 4′ aligned with the chimneys 6,6′ of the dimplings 5, 5′. Note the screws 7, 7′ in the holes 4 and 4′.The chimneys 6, 6′ can carry an internal thread whose pitch and othercharacteristics correspond to those of the screws. But, in practice,screws 7, 7′ are preferred, that is auto-threading screws, and then thechimneys are smooth inside.

It is understood that the end of the conveyor belt being introduced intothe space between the two halves of the fastener, upper and lower, it ispossible to pass the screws in the holes 4, 4′, and then to cross themthrough the thickness of the conveyor belt, the screws themselves makingtheir hole in the conveyor belt. When arriving at the level of thechimneys 6, 6′ of the dimplings 5, 5′, the self-threading screws attackthe inside of the chimney in which they are being screwed, finishing bytightening the two halves of the fastener. Once they have been screwed,the dimplings 5, 5′, as well as the reverse side of the cups 41, 41′ areembedded in the material of the end of the conveyor belt. The grip ofthe fastener thus does not come uniquely from the presence of the screwpassing through the conveyor belt, but also from the grip from thereverse side of the cups 41, 41′ and by the dimplings 5, 5′.

At this stage of the explanation, the flexibility claimed for thefixation of our new fastener has not yet been explained.

FIGS. 3 and 4 show the operational situations in which it is noted thatthe screws do not remain perpendicular to the upper and lower halves ofthe fastener.

Indeed, in FIG. 3, the screw is inclined in relation to the vertical;its head has slid into the cup, and the dimpling is also inclinedtowards the left.

In FIG. 4 the same inclination phenomenon, but this time towards theright, can be observed. This inclination, provoked by the strains of thepassage of the conveyor belt on the forward or backward rollers, is thereflection of the difference of the path of the two halves of thefastener during passage over the rollers. This difference of path, whichthe fastener can adapt to, is shown by the gap a, or −a, which affectsthe ends of the fastener in the situations represented respectively inFIGS. 3 and 4.

This inclination of the dimpling 5 (and the dimpling 5′ not shown) ismade possible by the fact that, as already noted in FIG. 1, the dimplingdoes not constitute a continuous step 8 over the whole of itscircumference. In fact, the step is suppressed in the circular sectors81, 82, 81′, 82′, that is to say in the parts of the dimpling which,when the fastener is used, are arranged in the longitudinal direction ofthe conveyor belt (operational direction). In addition, shearings of thesheet metal are carried out, which appear in FIGS. 3 and 4, as 91 and92. It is these which apart from the fact that they allow stamping ofthe step 8, also permit the tilting of the dimpling, which remains heldby the intact parts of its step 8, that is to say that the intact partswork elastically by pivoting slightly, in one direction or the other,which allows the inclination of the dimpling, that of the screw, thesliding of the head of the screw into the cup, and the shift (a or −a)of the ends of the halves of the fastener, upper and lower. This shiftthus authorised makes it possible to absorb without excessive strain thedifferences of path of the upper and lower faces of the conveyor belt,the dimpling returning to a normal position when the strains havedisappeared.

Thus, with the new fastener according to the invention, recourse to afixation mode rigid by definition, that is screwing, is compensated byan advantageous flexibility obtained by the original shape of thedimplings.

What is claimed is:
 1. Joining fastener for a conveyor belt, comprisingtwo fixation plates (2 and 3) linked by hinge elements (1) in a U-shape,presenting in one of the fixation plates (2 or 3) linked by the U-shapedhinge elements (1), holes (4, 4′) allowing the passage of a screw (7 or7′) and the gripping of its head and in the other fixation plate (3 or2), dimplings (5, 5′) which are oriented towards the first fixationplate (2 or 3), the screws (7, 7′) passed into the holes of the firstfixation plate (2 or 3) being able to be screwed in the dimplings whichare arranged aligned with the holes (4, 4′) corresponding to the firstfixation plate (2 or 3) when the fastener is tightened on one end of theconveyor belt, characterised in that each of the dimplings present attheir base steps (8, 8′ and 8″, 8′″) extending around a part of theirexternal circumference, but separated by two circular sectors (81, 82and 81′, 82′) diametrically opposite, without any steps, generallyoriented in the longitudinal direction of the conveyor belt on which thefastener according to the invention is set (or is to be set), thematerial of the fixation plate being sheared at the position of thesenon-deformed circular sectors in order to allow the formation of thestep partially surrounding the dimpling, by stamping the fixation platein which the dimplings are made.
 2. Joining fastener for a conveyor beltaccording to claim 1, characterised in that the chimneys (6, 6′) of thedimplings (5, 5′) are threaded, their diameter, their pitch and theirother characteristics corresponding to those of the screws (7, 7′). 3.Joining fastener for a conveyor belt according to claim 1, characterisedin that the holes (4, 4′) comprise an aperture in the shape of a cup(41, 41′).